I did it on a 950 in August with another R100GS and R1200GS (still haven't posted my report, I'm a slacker
). Our other friends were on smaller bikes.
I was really glad I took the 950, I enjoyed it more than I would've on a smaller bike, and we did all the difficult sections, excluding one due to time factor.
Nice report.....you're motivating me to work on mine !!